Specifications

EAW Smaart 6 Operation Manual Applications
88
Stabilizing a Sound System
Stabilizing an unstable system means giving it more GBF, primarily by reducing the
gain at the feedback frequencies. Although not a panacea or a substitute for good system
design, EQ is one of the most powerful tools to stabilize a sound system.
Smaart 6 can help identify feedback frequencies and apply precise EQ. But before you
start turning knobs, remember that EQ affects the overall frequency response of the
system. Other strategies might be equally or more effective and afford greater freedom
to make the system sound better.
Mechanical and Acoustical Solutions
The mic’s relative position to speakers and/or monitors can drastically affect the feedback
characteristics (frequency and amplitude). Reducing the gain at a problem frequency
can sometimes be as simple as using a different microphone or re-positioning a mic (a
strategy best employed with stationary mics).
Moving or redirecting speakers is also possible. Speakers placed close to (or behind)
microphones often cause feedback. In such cases it may be possible to add sound absorb-
ing material or a baffle to reduce the speaker’s field at the mic position or simply reduce
the speaker’s operating level. These solutions are obviously most attractive when they
can be applied without compromising the system’s design goals.
Educational Solutions
A stable system may become unstable when a certain number of microphones are open at
once. The best solution may be to train the operator to mute microphones when not in use.
Educating the performers in microphone technique can also be beneficial. Grabbing a
cardioid microphone, as many singers do, can increase its gain at certain frequencies
because the hand closes off the rear ports to the microphone element. Many performers
also point the mic at the monitor as they dance and move around the stage. Leaning too
close to a microphone can reflect energy at problem frequencies back into the microphone,
possibly causing feedback.
Electronic Solutions
Some reverberation devices and specific effect patches can destabilize an otherwise
stable system. If this occurs, experiment with other settings and/or reduce the overall
reverb level.
With a simple system, polarity or phase changes could solve a feedback problem im-
mediately. When the polarity is inverted, instead of positive feedback (negative impact
on sound) we should obtain negative feedback (possibly beneficial). However, in large,
complex systems with multiple return paths many wavelengths long, phase or polarity
changes is likely to merely shift the feedback frequency without increasing stability.